Air exhausting and cotton cleaning machine



1939- J. E. MITCHELL 2,166,925

AIR EXHAUSTING AND COTTON CLEANING MACHINE Filed Sept. 25, 1957 1 5/1702.- Ja/IN E. MITCHELL,

Patented July 18, 1939 UNITED STATES PATENT OFFICE AIR EXHAUSTING AND COTTON CLEANING MACHINE Application September 25, 1937, Serial No. 165,675

Claims.

The general object of the invention is to provide an improved machine that will operate to separate trash from the cotton as it is elevated from wagons to the distributor of a gin plant by an induced current of air, and with the same machine to exhaust or separate the air from the cotton,'while the latter is discharged, free of the air current, to the distributor or other machinery in the gin plant.

A particular object of the invention is to provide a comparatively fine-mesh screen within the machine over which the cotton sweeps when it first enters the machine, and through which a considerable portion of the air escapes, and a comparatively coarse or open-mesh cleaning screen over which the cotton is afterwards forced by a rotating member, and through which the balance of the air escapes with the trash.

A further object of the invention is to provide suitable means, preferably in the form of a rotating valve for periodically interrupting the movement, or decreasing the volume, of that portion of the air passing through the cleaning screen, to facilitate the movement of cotton over said screen.

My invention likewise involves a novel method of operation, which may be practiced by the machine illustrated in the accompaning drawing and hereinafter described: but the practice of said method is not dependent upon this particular form or construction of machine.

My inventionis illustrated in the accompanying drawing in which the View is a longitudinal section through a machine constructed according to my invention, the conventional driving mechanism being omitted and the directions of rotation of the various rotary members being indicated by arrows applied thereto.

Referring now to the drawing, the numeral I indicates the wind-trunk, or suction pipe, through which the cotton is elevated from the wagon and which is connected to the inlet 2 of the machine. The numeral 3 indicates a comparatively finemesh exhausting screen, which is curved rearwardly and downwardly from the upper side of the inlet 2, as shown. The upper end of the screen 3 is secured to a cross-beam 4 and its lower end to a cross-beam 5, both of these cross-beams and the screen, extending from side to side of the machine. Secured to the cross-beam 5 is one end of a relatively coarse-mesh screen 6 which is circula-r in formation, its opposite end being secured to a cross-beam 1 which, with the screen 6, extends from side to side of the machine. The screen 6 in effect constitutes a continuation of the screen 3, and together these screens constitute a screened member which surrounds all but a portion of the upper side of an agitating cylinder 8 rotating on an axis 9 and having arranged around its periphery longitudinal blades I 0. The sheet metal casing ll forms with'the screen 3 an air chamber l2 which communicates with a throat l3 formed by a transverse frame member M to which the lower end of the casing is secured and by a' shield I5, the upper end of which is secured to the cross-beam 5. The throat l3 communicates with a suction outlet It. The shield l5 extends downwardly to a point about midway of the suction outlet It and terminates in a comparatively narrow flat metal transverse member I! which, with a continuation l8 of the bot-tom of the suction outlet Hi, forms an air passage l9, in which is mounted a double-bladed rotating valve 20, which in its rotation serves to interrupt, or decrease the volume of, the air passing through the passage [9. The shield l5, and the continuation N3 of the bottom of the suction outlet I6 serves to form an air chamber 2| which communicates with the passage I9, said air chamber entirely surrounding screen 6.

The bottom of the inlet 2 is formed by a transverse frame member; 22, the bottom of which forms the top of an outlet 23 from the, space-inclosed by the screen members3 and 6. Rotating in this outlet-is a bladed discharge roller 24, which serves to discharge cotton elevated by the cylinder 3 through the outlet 23. Mounted immediately below this outlet to receive cotton therefrom is a valve chamber '2 5' in which is mounted a pocketvalve 26, the blades 2'! of which are adapted to rotate in sealing contact with opposite walls of the chamber 25. The upper side of this chamber is 'eontinued'into'a relatively wide opening 28 to receive cotton discharged through the outlet 23, and the bottom of the chamber provides an opening 29 through which cotton is discharged by the pocket-valve to the distributor. The pocketvalve rotating in sealing contact with the walls of the valve chamber "forms an air seal dropper, which permits cotton to be-continuously dischargedwhile at the'same time preventing an incoming current of air to the machine.

In operation, cotton el-evatedthrough the windtrunk I passes through the inlet 2, spreads out the full width of the machine and sweeps downward over the fine-mesh exhausting screen 3, through which most of the air passes and is drawn down through the air chamber 12 and throat It] to the exhaust outlet I5 which, as will be understood, is connected to the suction side of an exhaust fan. That portion of the air which does not pass through the fine-mesh exhaust screen 3 follows down around the periphery of the agitating cylinder 8 and passes through the comparatively coarse-mesh cleaning screen 5 and thence through the air chamber 2|, and passage [9 to the outlet IS.

The cotton passing over the screen 3 is engaged and forced by the agitating cylinder 8 over the cleaning screen 6 and delivered upward to the discharge roller 24, which delivers the same to the air seal dropper 26, which discharges it from the machine.

In order to fully present the advantages of my invention, as thus far described, a brief reference to existing conditions is necessary.

To elevate cotton from wagons to the distributor of a gin plant a large volume of air moved at high velocity is required; and while it is a simple matter to merely separate this large volume of air from the cotton after the cotton has been elevated, it is desirable at the same time to remove most of the trash; but the machines heretofore designed for this double purpose have, for a number of reasons, not been very successful.

One of the difliculties has been that the cotton is unloaded or elevated from the wagons in irregular quantities, and if the screen in a machine which separates the air from the cotton after it is elevated is sufilcient coarse, or open, to permit the free escape of trash, a sudden heavy load or mass of cotton entering the machine may cover enough of the screen at the same time to stop the movement of the cotton over the cleaning screen, which results in the screen being clogged and the cotton being badly roped or otherwise machined by any means employed for agitating or forcing it over the screen.

Such result, of course, is avoided in an ordinary air-exhauster, or separator, by merely having all of the screen (through which the air is drawn and over which the cotton passes) of sufficiently fine-meshes or perforations to prevent clogging by the cotton being drawn into the meshes. or perforations. Such a machine, however, while permitting the free exhaust or escape of the air, is of little or no value in removing the trash.

Referring now to the present invention, the upper screen 3 has relatively fine openings, preferably small perforations, and functions solely for permitting the continuous escape of a considerable portion of the air utilized for elevating cotton from the wagons, and for directing the stream of cotton passing over its interior surface onto the cleaning screen 6, which is provided with openings large enough to permit the trash to freely escape from the cotton with the remaining air which passes through the cleaning screen.

It will be obvious that the cotton entering the machine is carried by its own momentum downward along the interior surface of the fine-mesh screen 3, but must be mechanically agitated or moved over the coarse-mesh cleaning screen 6. which operation, in the present embodiment of the invention, is accomplished by the agitating cylinder 8, above referred to.

An important feature of my invention is to provide means to prevent any tendency for the current of air passing through the cleaning screen 6 to stop the movement of the cotton along the surface of the screen, and for this purpose I arrange to periodically interrupt the air current; or, in other words, to cause it to pass through the cleaning screen intermittently or in pulsations. This control of the air current is effected by the rotating valve 20. When this valve is in a horizontal position, as indicated by dotted lines, the maximum amount of air flows through the screen 6; but when it is in a vertical position, as shown by the solid lines, the minimum amount of air will pass through the cleaning screen; and since this interrupting valve is preferably rotated quite rapidly, it causes a pulsating current of air to pass through the cleaning screen, which not only serves the purpose of reducing the volume of air that must pass through the exhaust screen 3, but makes the cleaning screen more effective by intermittently permitting strong pulsations of air to pass through the screen with the trash, while also intermittently reducing the amount of air passing through the cleaning screen long enough to avoid interfering with the free movement of the cotton over the interior surface of said cleaning screen.

The shield I5, extending, as it does, from the top of the screen 6 to a point relatively near the bottom member l8, not only serves to provide, with said bottom member, the passage 19, but it also acts to prevent too much air being drawn through that portion of the cleaning screen nearest the outlet 4. Thus, suction is exerted only indirectly on that portion of screen 6 which is lying behind the shield I5.

It will be obvious that when the valve 20 is closed the greater portion of the current of air entering the inlet 2 will be drawn directly toward the screen 3, and will pass through the screen. On the other hand, when the valve 20 is open the amount of air passing through screen 3 will be decreased and a greater portion of the air will flow about the periphery of the cylinder 8 on both sides thereof and through the screen 6. Each action described is momentary; that is to say, the valve 20 is rotated rapidly to alternately partly close and then open passage IS, with the result that the air passes through screen 6 in pulsations. The resulting periods of slight suctions exerted on the screen 6 permits the agitating cylinder to readily force the cotton over this coarse screen.

I claim:

1. The method of separating air and trash from cotton which consists in continuously drawing cotton into a chamber by suction created on the farside of a screen member interposed in the path of the air current and having a finemesh and a coarse-mesh portion, directing the course of the cotton in said chamber successively over the surfaces of the fine-mesh and coarsemesh screens. periodically decreasing the volume of air passing through said coarse-mesh screen, and discharging the cotton passed over said coarse-mesh screen from the chamber.

2. The method of separating air and trash from cotton which consists in continuously drawing cotton into a chamber and into contact with and over a fine-mesh screen by suction created on the far side of said screen and a coarse-mesh continuation thereof, mechanically forcing the cotton from said fine-mesh screen over the coarse-mesh continuation thereof, periodically interrupting the suction exerted on the coarsemesh screen in rapid alternation, and continuously removing from the chamber the cotton which has been passed over said coarse-mesh screen.

3. An air exhausting and cotton cleaning machine comprising in combination with an inclosed chamber having an inlet for an induced current of air bearing the cotton, an outlet for the air bearing the trash, and an air sealed discharge outlet for the cleaned cotton, a rotatable cotton agitating cylinder mounted within the chamber having a stationary cleaning screen extending around its lower circumference and over which the blades of the cylinder are adapted to agitate the cotton, a deflecting screen extending from above the inlet of the chamber and serving to intercept and direct the cotton to the cleaning screen while permitting the passage of a portion of the air current therethrough, and means whereby the balance of the air current passing through the cleaning screen is intermittently increased and decreased in velocity to draw through said cleaning screen the trash loosened by the agitating cylinder without interrupting the movement of the cotton over the cleaning screen.

4. In a machine for cleaning cotton in a variable current of air, the combination of an inclosed chamber having an inlet for air and cotton on-one side and an outlet for the air and trash from the opposite side, a cotton agitating cylinder mounted within the chamber, a relatively coarse-mesh cleaning screen extending around the lower circumference of the cylinder, means for inducing a variable current of air through said cleaning screen, a supplemental screen of finer mesh than the cleaning screen extending from the latter to the upper portion of the chamber above the air and cotton inlet current passing through to direct the cotton to the cleaning screen and permit said cylinder to agitate the cotton thereover while permitting the passage through the screen of finer mesh of a portion of the air to lessen the velocity of the current of air forced through the cleaning screen.

5. In an air exhausting and cotton cleaning machine, in combination with an inclosed chamber having an air and cotton inlet and a cotton outlet at one side and an air exhaust outlet at the other side, a fine-mesh screen extending from above said inlet outwardly and downwardly across the plane thereof, a circular coarse-mesh screen forming a continuation of the fine-mesh screen and extending to a point adjacent the cotton outlet, an agitating cylinder mounted to cooperate with said coarse-mesh screen and adapted to engage cotton carried by the momentum of suction over said fine-mesh screen and force it over the surface of said coarse-mesh screen, a shield interposed between a portion 01' said coarse-mesh screen and said air exhaust outlet extending partway across the same and forming with the bottom of the casing of the machine a relatively narrow air passage, a rotatable valve mounted in said air passage for intermittently interrupting the velocity of the air said coarse-mesh screen, and means for continuously discharging the cotton carried overthe coarse-mesh screen from said chamber.

JOHN E. MITCHELL. 

